Hazardous materials--including certain chemicals, poisons, and biologic elements--require safety controls in their packaging and handling for transport. Like other liquid hazardous materials, infectious substances transported by air or road are required to be contained in packaging that meets certified pressure performance. Pressure vessel performance is based on the packaging's ability to withstand, without visible liquid loss, a pressure differential resulting from an internal pressure load. General diagnostic specimens, which in the work place typically are treated as infectious substances, also are subject to regulatory influences.
Packaging suppliers for hazardous materials currently use rigid molded plastic containers as supplementary packaging to prevent harmful agents from entering the environment. Examples of the rigid containers are described in U.S. Pat. Nos. 5,160,021, 4,882,893, 4,872,563, 4,842,153 and 3,819,081. Known rigid containers generally are designed to hold several specimens and meet international transport pressure requirements. The rigid containers' dimensional tolerance limitations often necessitate using gaskets to sustain an internal pressure load, especially as the size of the container's opening increases in diameter and as a consequence of an increased pressure differential between the interior of the container and its ambient surroundings. Although the containers are well suited for transporting multiple samples, they may become economically unacceptable when samples are shipped in small numbers. The container's cost relative to the need to ship the sample may preclude its use. Further, when large quantities are shipped, the rigid containers also can be economically unacceptable because so many of the relatively expensive rigid vessels are needed. General diagnostic samples, for example, often are shipped in lots of over two hundred, making rigid walled pressure vessels sometimes prohibitively expensive to use. Further, the rigid containers' non-collapsible nature can pose problems from a storage and shipping standpoint because they create additional dead space, which consequently consumes more volume and leaves less room for additional samples. Also, the rigid containers typically are made of an opaque plastic, making it difficult to see the status of the shipped sample (e.g., sealed, broken, full, empty, et cetera).
Plastic bags also are used to transport and handle both infectious materials and general diagnostic samples. Traditionally, plastic bags are used to hold filled specimen containers. Although the plastic bags when sealed can isolate the contents from its surrounding environment, the bags suffer from the disadvantage of not being able to maintain an internal pressure load that is even minimally higher than the ambient surrounding pressure. Related shipping bags--see, for example, U.S. Pat. Nos. 5,199,795 and 4,927,010--are known to have closures that span their full width. The sealing mechanisms described in these patents, whether mechanical or adhesive, also are susceptible to failure when confronted with internal pressure loads applied to the containment vessel.